The following commit has been merged into the core/rcu branch of tip:
Commit-ID: b6e2c4ed35c33d7e55197aa26d99645a690ca467
Gitweb: https://git.kernel.org/tip/b6e2c4ed35c33d7e55197aa26d99645a690ca467
Author: Frederic Weisbecker <frederic@xxxxxxxxxx>
AuthorDate: Tue, 23 Feb 2021 01:10:07 +01:00
Committer: Paul E. McKenney <paulmck@xxxxxxxxxx>
CommitterDate: Wed, 12 May 2021 12:10:23 -07:00
rcu/nocb: Cancel nocb_timer upon nocb_gp wakeup
When waking up in nocb_gp_wait(), there is no need to keep the nocb_timer
around because this function will traverse the whole rdp list. Any
update performed before the timer was armed will now be visible after
the ->nocb_gp_lock acquire.
Signed-off-by: Frederic Weisbecker <frederic@xxxxxxxxxx>
Cc: Josh Triplett <josh@xxxxxxxxxxxxxxxx>
Cc: Lai Jiangshan <jiangshanlai@xxxxxxxxx>
Cc: Joel Fernandes <joel@xxxxxxxxxxxxxxxxx>
Cc: Neeraj Upadhyay <neeraju@xxxxxxxxxxxxxx>
Cc: Boqun Feng <boqun.feng@xxxxxxxxx>
Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxx>
---
kernel/rcu/tree_plugin.h | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h
index 015adec..a667551 100644
--- a/kernel/rcu/tree_plugin.h
+++ b/kernel/rcu/tree_plugin.h
@@ -2211,6 +2211,10 @@ static void nocb_gp_wait(struct rcu_data *my_rdp)
raw_spin_lock_irqsave(&my_rdp->nocb_gp_lock, flags);
if (bypass)
del_timer(&my_rdp->nocb_bypass_timer);
+ if (my_rdp->nocb_defer_wakeup > RCU_NOCB_WAKE_NOT) {
+ WRITE_ONCE(my_rdp->nocb_defer_wakeup, RCU_NOCB_WAKE_NOT);
+ del_timer(&my_rdp->nocb_timer);
+ }
WRITE_ONCE(my_rdp->nocb_gp_sleep, true);
raw_spin_unlock_irqrestore(&my_rdp->nocb_gp_lock, flags);
}
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